Sec.  90.691   Emission mask requirements for EA-based systems.

   (a) Out-of-band emission requirement shall apply only to the “outer”
   channels included in an EA license and to spectrum adjacent to interior
   channels used by incumbent licensees. The emission limits are as follows:

   (1) For any frequency removed from the EA licensee's frequency block by up
   to and including 37.5 kHz, the power of any emission shall be attenuated
   below the transmitter power (P) in watts by at least 116 Log[10](f/6.1)
   decibels or 50 + 10 Log[10](P) decibels or 80 decibels, whichever is the
   lesser attenuation, where f is the frequency removed from the center of the
   outer channel in the block in kilohertz and where f is greater than 12.5
   kHz.

   (2) For any frequency removed from the EA licensee's frequency block greater
   than 37.5 kHz, the power of any emission shall be attenuated below the
   transmitter power (P) in watts by at least 43 + 10Log[10](P) decibels or 80
   decibels, whichever is the lesser attenuation, where f is the frequency
   removed from the center of the outer channel in the block in kilohertz and
   where f is greater than 37.5 kHz.

   (b) When an emission outside of the authorized bandwidth causes harmful
   interference, the Commission may, at its discretion, require greater
   attenuation than specified in this section.